Re: Two neutron stars on a collision course?

On 2008-03-08, Crown-Horned Snorkack <chornedsnorkack@[EMAIL PROTECTED]
> wrote:
> Why would the pressure convert into heat?

The pressure doesn't directly convert into heat.  The reduction in
density allows neutrons to decay.  The decay energy converts into
heat.


> Besides, if the density reduction is slow, the heat would be removed
> by conduction.

I was considering a slow adiabatic expansion.  It's all a thought
experiment anyway: there is no known way to slow expand degenerate
neutron matter.  In colliding neutron stars, the vast majority of any
core matter that escapes will just expand into a free neutron gas and
decay into hydrogen plasma.


> If you had high pressure, high electron chemical potential and low
> temperature

Well, that's fundamentally where we differ: you think the temperature
will drop by at least an orders of magnitude before electron
degeneracy ceases affecting nuclear reactions.  I don't.

But let us suppose you were right, and we started with isolated and
contained sample of pure tritium at negligible temperature and
pressure in nuclear terms.  As I see it: even with a 12 year half
life, each day there would be about 3 keV/atom of heat energy from
decay added to the system.  It won't be long at all before we get
significant fusion and an extremely rapid increase in heat up to a few
MeV/nucleon.

Yes, we will get lead-208 in some equilibrium mix, but it will be
particularly short-lived with respect to the ongoing reactions.  As
the temperature drops (but still while plenty of nuclear interactions
are taking place), types of nuclei that have very few energetically
favourable reactions with other nuclei will come to dominate.

Those most common nuclei won't include high-energy types such as
tritium or lead-208.  They may be present in trace amounts.


- Tim